Display screen or portion thereof with a graphical user interface for messaging



FIG. 1 is a front view of a display screen or portion thereof with a first embodiment of a graphical user interface for messaging showing the new design; and,

FIG. 2 is a front view of a display screen or portion thereof with a second embodiment of a graphical user interface for messaging showing the new design.

The dashed broken line showing of a display screen or portion thereof with a graphical user interface is included for the purpose of illustrating portions of the article and forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with a graphical user interface for messaging, as shown and described. 